Computed Tomographic Colonography (CTC) is a minimally invasive method for the examination of the colon using spiral/helical CT volume data. The standard imaging process includes colon cleansing and air-insufflation, followed by CT imaging of the abdomen while the patient is in the supine position. However, insufficient cleansing and air-insufflation often cause some parts of the colon wall to be covered with water (See e.g. S. C. Chen et al., “CT colonography: value of scanning in both the supine and prone positions,” Am J Roentgenol, vol. 172(3), pp. 595–599, 1999; J. G. Fletcher, et al., “Optimization of CT colonography technique: prospective trial in 180 patients,” Radiology, vol. 216(3), pp. 704–711, 2000; J. Yee, et al., “The usefulness of glucagon hydrochloride for colonic distention in CT colonography,” Am J Roentgenol, vol. 173(1), pp. 169–172, 1999). Furthermore, retained solid fecal material can mimic a polyp in CT images (See e.g. J. G. Fletcher et al., “CT colonography: potential pitfalls and problem-solving techniques,” Am J Roentgenol, vol. 172(5), pp. 1271–1278, 1999 (With comments in Am J Roentgenol, vol. 172(5), pp. 1179, 1999)). These limitations are largely overcome by imaging the colon a second time with the patient in the prone position. The radiologists then compare the two sets of images to assess for movement of feces and to examine surfaces hidden in supine position. This requires careful anatomic alignment between the two data sets. However, as the patients change position, their colons deform and may stretch or shrink in length. Currently, anatomic matching the two data sets is tedious and time consuming. Accordingly, there is a need for a more convenient and automatic method that would allow matching of these two data sets.